I don't really measure when I cook unless following a recipe. so use your discretion as to amounts. IMO a 3 egg omelette needs a 12" pan I didn't realize this till I owned one. they were always to thick in a 10 or smaller so use 2 eggs for those.

Heat non stick pan with olive oil

Add spinach and saute -stir and flip using tongs. I like to salt the spinach but with all the salt in the feta I am not sure it is really necessary

Add crushed garlic and garlic powder Obviously you can and should substitute fresh minced Garlic if you have it

crack eggs into bowl and scramble well to fully incorporate the yolks and whites

Once the spinach has cooked down remove from heat and set aside.

Wipe clean pan and place back on heat add butter just enough to coat pan. I just hold the wrapped stick so not to add to much

Add scrambled eggs once the butter starts to foam allow eggs to set adjusting heat as necessary

add sauteed spinach and crumbled feta cheese

Pepper to taste once the eggs are almost fully cooked fully cooked flip 1/3 of the omelette into itself slide the open side onto the plate and flip it off pan